Running the Pact protobufs-over-HTTP proof of concept

pact-protobuf-poc.md

Introduction

This gist describes how to run the proof of concept for protobufs-over-HTTP for the Pact framework.

It's worth noting that this work isn't yet in a production-ready state, and at this stage is a first illustrative step of what can be done in this space.

The ideas implemented here, are described in this presentation.

The pact-serialization-proxy component referred to in the presentation has a repo which can be found here.

Example Pact-user code

• Try to get a protobuf object as a Pact consumer https://github.com/mcon/pact-net/blob/protobuf-serialization/Samples/EventApi/Consumer/EventsApiClient.cs#L243

• Orchestration changed to use pact-serialization-proxy in addition to the Ruby core as per the archetecture diagram https://github.com/mcon/pact-serialization-proxy#design: https://github.com/mcon/pact-net/blob/protobuf-serialization/Samples/EventApi/Consumer.Tests/ConsumerEventApiPact.cs#L30

• Test that consumer can get protobuf object: https://github.com/mcon/pact-net/blob/protobuf-serialization/Samples/EventApi/Consumer.Tests/EventsApiConsumerTests.cs#L353

• Create a server which returns a protobuf-serialized response https://github.com/mcon/pact-net/blob/protobuf-serialization/Samples/EventApi/Provider.Api.Web/Controllers/PersonController.cs

• No change required to the verification code, as the PoC mandates the use of the pact-serialization-proxy

Instructions

Get the pact-serialization proxy

Option 1: download the binary from GitHub (currently Linux only)

https://github.com/mcon/pact-serialization-proxy/releases

Option 2: build from source

• Install golang https://golang.org/doc/install - I used 1.12.5 linux/amd64 -- Go to your GOPATH

cd `go env | grep GOPATH | cut -d = -f 2 | tr -d '"'` 
go get github.com/mcon/pact-serialization-proxy/cmd/proxy-server
cd src/github.com/mcon/pact-serialization-proxy
make build
PACT_PROXY_SERVER=realpath proxy-server

• Note down the fully qualified path of the proxy server binary

Get the .NET pact branch with protobuf proof of concept

• Download .NET core: https://dotnet.microsoft.com/download - I used version 2.1.802

mkdir ~/proto-example
cd !$
git clone https://github.com/mcon/pact-net.git --branch protobuf-serialization
cd pact-net

• Swap out hacked hard-coded location of pact-serialization-proxy with your version

find . -name "*.cs" | xargs -i sed "s|/home/matt/go/src/github.com/mcon/pact-serialization-proxy/proxy-server|$PACT_PROXY_SERVER|g" -i {}

• Generate consumer contract

dotnet test Samples/EventApi/Consumer.Tests/

• Note that the generated contract has an entry with an "encoding" field:

cat Samples/EventApi/Consumer.Tests/pacts/event_api_consumer-event_api.proto.json

• Verify the pact contract

dotnet test Samples/EventApi/Provider.Api.Web.Tests/

Note: sometimes the pact-serialization-proxy isn't shut down correctly (the .NET code I've hacked together isn't terribly robust), pkill proxy-server should kill it.